The rare gases or noble gases are members of the zero group or Group VIII A of the perioidic table. The rare gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).
The discovery of rare-gas halide lasers opens up the field for efficient, high power coherent light sources in the ultraviolet (UV) portion of the spectrum. This portion of the spectrum being just beyond the violet or the short-wavelength side: generally 180-3900 angstroms.
Prior art in self-sustained discharge pumped rare gas halide excimer lasers exhibited lower than desired efficiencies and limited potential for scaling the high average power light sources.
The self-sustained discharge pumped rare gas-halide RGH) lasers that have been developed to date have used a single, strongly attaching halogen donor. The use of a single, strongly attaching halogen donor hinders optimization of the performance of these lasers because the halogen donor simultaneuosly affects laser performance in several ways. The various roles of the halogen donor are summarized in Table I. With a single halogen donor the halogen donor concentration which gives the best laser performance, [XHn].sub.opt, is determined by a trade-off between achieving high energy deposition, which occur at low values of [XHn], and high excited rare gas-halide (RHn*) production efficiency, which occurs at high values of [XHn]. It should be noted that the values of [XHn] range from .about.0.1% up to .about.10% for the purposes of this discussion. Furthermore, in many of the present RGH lasers most of the so-called "metastable channel" for RHn* production: EQU R*+XHn.fwdarw.RHn*+X (1)
is almost unused, and most of the RHn* production is via the other possible RHn* production channel, the "ion recombination channel": EQU R.sup.+ +HN.sup.- +M.fwdarw.RHn*+M (2).
TABLE I ______________________________________ Energy Controlling Role of the Halogen Conversion Step Factor(s) Donor (XHn) ______________________________________ (1) Deposition of Maximum energy and Maximum power/ electrical power limited by the energy increases as energy in the glow-to-arc pulse length and XHn discharge transition concentration increase (2) Production of Production efficiency Production efficiency excited rare determined by the peaks at optimum gas-halide gas mixture XHn concentration (RHn*) (3) Extraction of Extraction efficiency Extraction efficiency laser photons determined by RHn* peaks at optimum production rate and pulse length, pulse length. increases as RHn* production increases ______________________________________
In equations (1) and (2) R* and R.sup.+ are, respectively, excited rare gas atoms and rare gas ions. Hn is the halogen (e.g. F, Cl, etc.) and M is a third body needed to stabilize reaction (2).
A reaction scheme to achieve improved performance by enhancing the efficiency of the energy exchange or energy conversion step would be of major significance in the Rare Gas-Halide Laser Art.
Therefore, an object of this invention is to provide a reaction scheme or mechanism whereby improved performance is obtained by using two halogen donors instead of one.
A further object of this invention is to provide two halogen donors wherein each donor is selected to perform a separate specific function whereby the combined functions result in improved performance of a rare gas-halide laser.